1. Field of the Invention
The present invention relates to a recording unit which can record at a high quality or to an apparatus having such a recording unit and, more particularly, to a technique to control a recording energy.
2. Related Background Art
Hitherto, as printers for recording a pattern such as characters, graphics, or the like, for example, a thermal transfer printer using a heating energy has been developed.
In recent years, a thermal transfer printer which can attach a plurality of kinds of ribbons is also being developed. However, as a method of controlling the thermal heads, only a method of controlling, e.g., a width of heat pulse or the like and a conventional similar method are used. The high quality recording is not always performed in dependence on the kind of ribbon. A further improvement is demanded.
As a method of correcting the heating energy upon recording in a thermal transfer printer, there is considered a method whereby one pulse or two pulses of different widths are output within one heat cycle when dot information to be recorded exists on the basis of the on/off of the dot pattern which is obtained from a character generator CG, thereby changing an energy to be applied and eventually uniforming the heating energies. However, the method of uniforming the heating energies to the dots within one heat cycle of the dots to be recorded has a drawback such that the high quality recording is not always obtained.
Further, as a method of improving this drawback, there is considered a method whereby a preheat is given even in the cycles other than one heat cycle for recording to thereby uniform the heating energies. However, when the preheating position is away from the position to be printed, particularly, in a low speed printer or the like, it is presumed that the expected uniformity of the heating energies is not obtained.
On the other hand, when improving as mentioned above, namely, when the preheat is given in the cycles other than one heat cycle to be recorded, particularly, the ambient temperature of one independent dot is low, so that the heating energies escape. For example, at the left end of the pattern to be recorded, the heating energies in the upper, lower, right, and left directions escape. Thus, it is presumed that the high quality recording cannot be performed.
The foregoing drawback is particularly typical in the case of recording an underline.
In addition, even when improving as mentioned above, for example, in the case of recording such patterns as shown in FIGS. 20 and 21, if the A data indicated by broken lines was heated by the foregoing method, it is considered that the blank portions in the " ", " ", and ".hoarfrost." shapes are deformed.
For example, as shown in FIG. 22, when recording such a pattern that the areas in the peripheral four directions are surrounded by the dots to be recorded, if the A data indicated by broken lines and further the M data as dot information were heated by the foregoing method, it is considered that the heating energies are concentrated to the central dot and a variation in heating energy occurs.
As a method of eliminating the foregoing drawbacks, there is considered a method whereby in the recording cycle before the first recording cycle of the dot information to be recorded, the preheating energy is given in the cycle near the second recording cycle. However, there is a fear such that the heating energies are unstable and the uniform recording cannot be executed until the second recording cycle to record the next dot information to be recorded.